From the top left to the right, first row: (a) error produced by CIR# and (b) error produced by HW model; from the top left to the right, second row: (a) forecasting error with the EWMA and (b) forecasting error with the ARIMA-EGARCH*; from the top left to the right, third row: (a) forecasting error with the SARIMA* and (b) forecasting error with the DNNAR*